In the J2EE server usrconf.cfg file, if you specify the options shown in the table below, you can acquire extended verbosegc information. From the extended verbosegc information, you can acquire the information for estimating the Java heap area size, Perm area size, required for that server. Note that the stack trace at OutOfMemoryError occurrence time is also output in the Java log.

Table 5-24 Options to be specified for acquiring the extended verbosegc information

Optional	Meaning
-XX:+HitachiVerboseGC	Specify whether to output the extended verbosegc information. Output information for each Eden, Survivor, Tenured, Perm type that is the internal area of garbage collection. Nothing is output by default. If -XX:+HitachiVerboseGC is specified, the extended verbosegc information is output and if -XX:-HitachiVerboseGC is specified, the extended verbosegc information is not output.
-XX:+HitachiVerboseGCPrintDate	Specify whether to display the date of log output at the beginning of each line of the log in which the extended verbosegc information is output.
-XX:+HitachiVerboseGCCpuTime	During the period between the start of garbage collection until the end of garbage collection, specify whether only the time spent in user mode and kernel mode by the garbage collection execution thread should be displayed or the execution time should be displayed. However, this function cannot be used when HP-UX is used. Even if this option is specified it is invalid.
-XX:HitachiVerboseGCIntervalTime=Time-interval	Specify a numeric value (Unit: Seconds) as an output time interval for -XX:+HitachiVerboseGC. The default value for the time interval is 0 (Output every time garbage collection occurs). Note that when you specify the time interval, the garbage collection frequency during that time interval is also displayed.
-XX:+HitachiVerboseGCPrintCause	Specify whether to display the cause for the occurrence of garbage collection in the log in which the extended verbosegc information is output.
-XX:+HitachiCommaVerboseGC	Specify whether the log in which the extended verbosegc information is output should be in CSV format. If the log is output in the CSV format, all the brackets (( ) [ ] < >) and delimiters of the extended verbosegc information are omitted, and the numeric values or character strings delimited by comma (,) are output.
-XX:+HitachiVerboseGCPrintTenuringDistribution	Specify whether to output Tenuring Distribution information of Survivor area. Nothing is output by default. For output format or output information, see 9.11 Tenuring distribution information output functionality of the Survivor area.
-XX:+HitachiVerboseGCPrintJVMInternalMemory	Specify whether the heap information managed in JavaVM is output to the JavaVM log file.
-XX:+HitachiVerboseGCPrintThreadCount	Specify whether the Java thread count is output to the JavaVM log file to monitor the Java thread count.
-XX:+HitachiVerboseGCPrintDeleteOnExit	Specify whether the cumulative heap size allocated by JavaVM by invoking java.io.File.deleteOnExit()and the frequency of method invocation are output to the JavaVM log file.
-XX:+PrintCodeCacheInfo	Specify whether to output the usage of the code cache area, and also whether to output a message informing the user that the usage has reached the threshold value.

The format and the example of the log file output are as follows:

Output format

[id]<date>(Skip Full:full_count, Copy:copy_count)[gc_kind gc_info, gc_time secs][DefNew::Eden: eden_info][DefNew::Survivor: survivor_info][Tenured: tenured_info][Perm: perm_info][cause:cause_info][User: user_cpu secs][Sys: system_cpu secs] ][IM:jvm_alloc_size, mmap_total_size, malloc_total_size][TC: thread_count][DOE: doe_alloc_size, called_count] [CCI: cc_used_sizeK, cc_max_sizeK, cc_infoK]

Description

• id: JavaVM log file identifier
  The following table describes the JavaVM log file identifiers. Use these identifiers for investigation by filtering log as per log contents (functions).
  

  Table 5-25 JavaVM log file identifiers

  Identifiers	Log contents
  CCI	Code cache area information
  CLT	Stack trace of class library
  JCC	Information on the failure of JIT compilation
  JMS	Information on the JIT complier thread that prevents JIT compilation
  OMH	Information on the frequency of OutOfMemory occurrences
  OOM	Exception information when OutOfMemoryError occurs and stack trace
  PTD	Tenuring distribution information of Survivor area
  VGC	Extended verbosegc information

• date: Date and time
• full_count: Frequency of skipping full garbage collection (Only when you specify -XX:HitachiVerboseGCIntervalTime)
• copy_count: Frequency of skipping copy garbage collection (Only when you specify -XX:HitachiVerboseGCIntervalTime)
• gc_kind: Garbage collection type (Full GC or GC)
• gc_info: Garbage collection information (Area length prior to garbage collection-> Area length after garbage collection (Area size))
  (Example) 264K->0K(512K)
  
• gc_time: Garbage collection elapsed time (Unit: Seconds)
• eden_info: Eden information
• survivor_info: Survivor information
• tenured_info: Tenured information
• perm_info: Perm information
• cause_info: Cause of garbage collection
• user_cpu secs: CPU time spent in user mode by the garbage collection thread (Unit: Seconds)
• system_cpu secs: CPU time spent in kernel mode by the garbage collection thread. (Unit: Seconds)
• jvm_alloc_size: The size of the area currently in use, among the areas managed in JavaVM (size of the area currently in use among the total size of mmap_total_size and malloc_total_size) (only when -XX:+HitachiVerboseGCPrintJVMInternalMemory is specified)
• mmap_total_size: The total size of C heap allocated by mmap (in Windows VirtualAlloc) , among the areas managed in JavaV (only when -XX:+HitachiVerboseGCPrintJVMInternalMemory is specified)
• malloc_total_size: The total size of C heap allocated by malloc, among the areas managed in JavaVM (only when -XX:+HitachiVerboseGCPrintJVMInternalMemory is specified)
• thread_count: Java thread count (only when -XX:+HitachiVerboseGCPrintThreadCount is specified)
• doe_alloc_size: The accumulated heap size allocated by invoking java.io.File.deleteOnExit() (only when -XX:+HitachiVerboseGCPrintDeleteOnExit is specified)
• called_count: The number of times java.io.File.deleteOnExit() is invoked (only when -XX:+HitachiVerboseGCPrintDeleteOnExit is specified)
• cc_used_size: Size of the code cache area used during garbage collection (unit: kilobyte) (only when -XX:+PrintCodeCacheInfo is specified)
• cc_max_size: Maximum size of the code cache area (unit: kilobyte) (only when -XX:+PrintCodeCacheInfo is specified)
• cc_info: Maintenance information (only when -XX:+PrintCodeCacheInfo is specified)

Example of output

Examples of output when the -XX:+HitachiCommaVerboseGC option is specified are as follows:

VGC,Fri Jan 23 21:37:50 2004,11,41,0,GC,16886,16886,65088,0.0559806, 4094,0,4096,447,447,448,12345,16439,60544,1116,1116,4096,0,0.0312500, 0.0156250,729,928,0,509,2167,2054,2301,49152,2304 VGC,Fri Jan 23 21:37:55 2004,6,24,0,Full GC,65082,65082,65088,0.4294532, 4094,4094,4096,447,447,448,60541,60541,60544,1116,1116,4096,0,0.0156250, 0.0312500,729,928,0,509,16,170,2301,49152,2304